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Thread: how much dry acid sulfite problem

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    how much dry acid sulfite problem

    Hi,
    I have about 30lbs of dry acid left from last year (new pool plaster). I'm now comfortable using muriatic acid btw----but i have all this left over dry acid. My pool is still needing 12 oz of muriatic acid a day. I realize dry acid adds sulfites, which apparently damages the pool. But how much of the left over acid can i safely use, before switching back to liquid?
    Thanks
    16,000 gallon, inground. Diamond bright finish. Hayward 1.5 hp superpump, quad 80 DE filter, Jandy legacy gas heater

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    Join Date
    Mar 2007
    Location
    San Rafael, CA USA
    Posts
    12,082

    Re: how much dry acid sulfite problem

    Based on this thread, the limit of sulfates to prevent concrete/plaster problems is around 300 mg/L (ppm). If you are starting with near zero, then in your 16,000 gallon pool you'd get 300 ppm sulfate after adding cumulatively 800 ounces weight (50 pounds) of dry acid (93.2% sodium bisulfate). And that assumes no water dilution.
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

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    Re: how much dry acid sulfite problem

    Mr. ChemGeek--thanks. Is it unusual at 11 months after replaster to still use so much acid? I was forced to acid wash due to scale 4 weeks ago (my numbers got out of hand last year after the replaster). Could the acid wash refreshening be contributing?

    I'm using about 12 oz muriatic a day, usually one "acid demand" drop worth from the taylor kit--about 0.2 rise in ph a day.


    TA 110
    CH 170
    CYA 25
    Borates 50
    PH 7.4-7.8
    FC 2-5
    CC always 0


    Thank you to this forum!!!!!!!!!!!!!!!!!!!111
    16,000 gallon, inground. Diamond bright finish. Hayward 1.5 hp superpump, quad 80 DE filter, Jandy legacy gas heater

  4. Back To Top    #4

    Join Date
    Mar 2007
    Location
    San Rafael, CA USA
    Posts
    12,082

    Re: how much dry acid sulfite problem

    Try lowering your TA to 70 ppm and see if that helps. If it does, then raise your CH level since it's on the low side and you should have more if you're going to have a lower TA. Also, don't lower the pH below 7.5 and let it get to 7.8 before you add acid.
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

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